Example of FileChannel in Java NIO Channels
November 20, 2013
FileChannel belongs to the package java.nio.channels and do reading, writing and updating the files. FileChannel keeps a current position that can be modified. FileChannel can do even more task. It can read and write bytes, transfer byte to other channel and can lock some part of file if required. FileChannel is thread safe in multithreaded environment. Find an example which will read a file.
FileChannelTest.java
package com.concretepage.nio.channels;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
public class FileChannelTest {
public static void main(String[] args) throws IOException {
FileInputStream fin = null;
FileChannel fchannel = null;
try{
//opens a file to read from the given location
fin = new FileInputStream("C:/temp/test.txt");
//returns FileChannel instance to read the file
fchannel = fin.getChannel();
//allocate byte buffer size
ByteBuffer byteBuffer = ByteBuffer.allocate(512);
while(fchannel.read(byteBuffer) > 0){
//limit is set to current position and position is set to zero
byteBuffer.flip();
while(byteBuffer.hasRemaining()){
char ch = (char) byteBuffer.get();
System.out.print(ch);
}
//position is set to zero and limit is set to capacity to clear the buffer.
byteBuffer.clear();
}
}catch(IOException e){
e.printStackTrace();
}finally{
fin.close();
fchannel.close();
}
}
}
